1. Field of the Invention
The present invention relates to a solvent enabling reduction in the volume and recycling of polystyrene foam or expanded polystyrene, and, in particular, to a method for recycling polystyrene foam materials.
2. Description of the Prior Art
In recent years, it is desired, from the view point of waste-disposal, to establish a recycling technology of the polystyrene foam used as a buffer or shock-absorber material.
Disposal of the polystyrene foam has hitherto been performed by heat-treatment in general. The reduction of the volume of the polystyrene foam by the heat-treatment however suffers from a disadvantage that the physical property of the polystyrene material is deteriorated by the applied heat and the resultant contraction of the material.
Researches on new methods for recycling the polystyrene foam by means of dissolution are being made for replacing the heat-treatment, because the new methods are considered to have a relatively small influence on the deterioration of the physical property of the material. At present, it is proposed to use d-limonene, which is one of citrus plant essential oils, as a solvent for the dissolution method.
The solvent, d-limonene, used in the above-mentioned dissolution method has an excellent ability for dissolving the polystyrene foam. The d-limonene however has a disadvantage that it has a strong citrus odor and a low flash point of 47.degree. C., and thus influences an operating environment. It is also liable to decompose and lacks stability, because it is a natural product.